Solvent extraction apparatus



March 20, 1951 W BlLBE soLvENT EXTRACTION APPARATUS 2 Sheets-Sheet 1 Filed May 5, 1945 Jal/0 MA TER/A L LEVL QTLET ll-IIlI-I March 20, 1951 c. w. BILBE soLvENT EXTRACTION APPARATUS 2 Sheets-Sheet 2 Filed May 5, 1945 AAM/Kaw lPatented Mar. 20, 1951 UNITED 4STATES PATENT OFFICE 'SOLVENT EXTRACTION APPARATUS Charles W. .Bilbe, Wauwatosa, Wis., rassignor to AAllis-,Chalmers Manufacturing Company, `Milwaukee, Ws.acorporation of Delaware 'Application May 5, 1945, Serial No. 592,190

2 Claims.

r1 The present invention relates generally to improvements in the art of treating materials and relates more particularly to improvements in methods and apparatus `for the `continuous countercurrent solvent extraction of solid materials,

It has heretofore been proposed to remove fats, oils and like substances .Ifrom Various lanimal and vegetable materials by the' use of suitable solvents. This removal or :separation vofoily Vsubstances or -the like Yfrom solid materials such :as soybean, vcottonseed 4and nut meal `:may be eiected .either sby the `treatment .of t'he material in batches or by the 'continuous treatment thereof. The `prs- :entzinvention is primarilycnncerned with .the pro- '.vision I,of .an improved method and apparatus .whereby'solvent extraction-.maybe eiectively *accomplished in a continuous, tuninterrupted .and .economical manner.

In the continuous solventextractionfof mate- `rials, it is common practice to advance thelmaterial through a bath of countercurrently -.moving vsolvent and then drainorsqueeze Athe liquid from the more or less exhaustedmaterial prior to discharging such materialto a drier for subsequent treatment. One 'type of apparatus hereto-fore proposed for effecting such continuous countercurrent solventextraction consists, generally, in the provision of an upright tank. "having an Vinlet for .solid materialat the `upper portion and an outlet for such material at the lower yportion with a conveyer forremoving ythe material from the outlet to a point .of discharge to the drier. The tankin such prior artapparatus isnormally provided with a screened outlet in the upper portion for theescape ot liquid, including the solvent and extracted oil, and the conveyer is provided with, or is associated with, means foreffecting partial separation of the liquid .'irom the solid material.

As to the means for effecting such partial separation, :one type of prior art apparatus in- .cludes an elevating conveyer of su'icient length vas to extend Well above "the solventlevel established by the liquid .outlet and provided With,.perforated conveyer members for vpermitting partial 'drainage of the vliquid by gravity back to the solvent level within vthe conveyer. In other instances the conveyer is movedthrough a perforated casing v'section `above the Yliquidlevelto permit partial drainage `ofthe'liquid-through a wall of the conveyercasing'where it is caught and returned tothe extraction-apparatus. In still other prior art systems, thematerial is sub- `jected to pressure either Withinthe conveyer or externally thereof and above the 'liquid levelto vtheplace `of drainage'or squeezing of the material. -f

Although systems provided -with an elevating conveyer in which drainage is permitted either `through "a perforated portion of the conveyer 'casing or within the conveyer passage, per se, have Aenjoyed a certain degree of commercial success, there are nevertheless numerous disadvantages attendant such installations. One of the Amajor objectionsfto thistype of apparatus is-that 'the conveyer must-be exceedingly long,'extending ra sulicient distance above the solvent level to'permit :a satisfactory separation by drainage of the liquid fromthe solid, Consequently, the original cost of this equipment is great and a large enclosure for the solvent extraction `plant is necessary. TLikewise, the `material must be advanced fat an objectionably slow speed, in conveyers of 'the drainage type, to'provide adequate drainage time and consequent separationprior to discharge of the solid-'material to the driers. Furthermore, apparatus oi this type is not generally satisfactory for use With all materials since some materials, such as flaxseed, consist of nely divided lparticles which either clog the perforations or are carried therethrough with the liquid. Another serious diiculty encountered with this type of equipment is in the constant need for cleaning and maintenance thereof. Since the majority of .the materials processed contain a relatively large proportion of iine particles, the perforations provided for the draining ofthe liquid constantly become clogged, necessitating frequent stoppages in the operation of the unit to clean the perforated portions of vthe conveyer or its casing for proper functioning of the unit. Therefore, not only is the maintenance cost high but ,the necessary interruptions in operation are costly.

Similarly, numerous disadvantages are attendant the various mechanical separating means heretofore proposed. One ofthe principal objections to the-use of ymechanical separators in `solvent extraction systems is in the diiiiculty which is encountered in providing and maintaining an operative device. Mechanical separators heretofore proposed have been disposed above the solvent level in the conveyer or externalh7 of both the conveyer and the solvent bath in the conveyer; and such devices have proven ineffective due to the fact that the saturated material, which is in the nature of a plastic mass and extremely diiiicult to handle after leaving the solvent bath, packs tightly when subjected to pressure, sticking and jamming in the various parts of the mechanical separating device and necessitating almost constant cleaning and maintenance attention. It has also been heretofore proposed to provide mechanical means at the lower outlet of the initial extraction chamber for feeding the material against pressure directly to the drier and eliminating the conveyer. However, the vertical arrangement of the large equipment, including the extraction chamber, separating device and drier, in such systems is highly impractical because of the objectionable resulting height. Furthermore, the pressure head against which such separating devices must operate is extremely great with a correspondingly high packing pressure necessary to effectively squeeze the liquid from the material being discharged; and failure of the separating mechanism, when located below the initial extraction chamber, results in the flooding of the drier. In addition to the foregoing objections to mechanical separators as heretofore proposed, the majority of these devices produce an undesirable and excessive comminution of the solid material being processed.

It is therefore an object of the present invention to provide an improved method and apparatus for solvent extraction which obviates the objectionable features of the prior methods and devices.

Another object of my invention is to provide an improved solvent extraction method and apparatus which is highly eicient in the removal of oils and like substances from solid materials and wherein separation of the liquid from the solids is speedily and effectively obtained in a continuous manner.

Another object of this invention is to provide an improved solvent extraction apparatus which is of simple construction, which is inexpensive to manufacture and operate, and which occupies a minimum amount of space both as to oor area and height.

Another object of the invention is to provide an improved solvent extraction apparatus wherein all parts are readily accessible for examination, replacement or repair.

Another object of my invention is to provide an improved solvent extraction apparatus wherein separation of the liquid from the solid material is effected by means of an independently operating mechanical separator which may be adjusted independently of its associated apparatus as to both speed and pressure, and with which a maximum degree of separation may be obtained prior to discharge of the solid material to the drier for removal of the remaining solvent by evaporation.

Another object of the present invention is to provide an improved method and apparatus for Solvent extraction wherein maximum separation of the liquid from the solid material is effected in a continuous manner by discharging the material against pressure `and while under a bath 4 of fresh solvent, without undesirably affecting the characteristics of the final products.

A further object of the present invention is to provide an improved method of solvent extraction comprising, moving a body of material through a body of counterflowing solvent in an initial extraction chamber, removing the material from the initial chamber and elevating it through a column of other solvent, separating the material from the solvent in the column beneath its upper extremity, and utilizing the solvent column height to maintain the initial chamber constantly lled with solvent.

An additional object of my invention is to provide an improved solvent extraction apparatus comprising, a primary extraction chamber having a solid material inlet, an elevating conveyer for removing solid material from the primary chamber, means for constantly maintaining the chamber and the conveyer lled with solvent, and means for removing solids from an upper portion of the conveyer below the level of the solvent therein.

Additional objects and advantages of the present invention will be apparent from the following detailed description.

A clear conception of the present improvement and of the mode of constructing and of utilizing apparatus built in accordance with my invention may be had by referring to the drawing accompanying and forming a part of this specification, wherein like reference characters designate the same or similar parts in the various views.

Fig. 1 is a part sectional side elevation showing an apparatus constructed in accordance with my invention and adapted to perform the several steps of my improved method;

Fig. 2 is a horizontal sectional view taken along the line II-II of Fig. 1;

Fig. 3 is a vertical sectional view taken along the line III-III of Fig. 1;

Fig. 4 is a vertical sectional view taken along the line IV-IV of Fig. 1;

Fig. 5 is a fragmentary front elevation of the discharge portion of a modif-led form of apparatus;

Fig. 6 is a horizontal sectional view taken along the line VI-VI of Fig. 5; and

Fig. '7 is a vertical sectional view taken along the line VII-VII of Fig. 5.

Referring to the drawings and more particularly Figs. 1 to 4 thereof, the improvedapparatus comprises in general an upright member I9 forming the primary extraction chamber, an elevating conveyer II associated with the lower portion of the chamber, and a pair of final extraction, washing and separating chambers or chests I2, I3 disposed on opposite sides of the conveyer and communicating with a drier I4.

As shown in the drawings, the primary extraction chamber I0 is provided with an upper solid material inlet I6 and a lower solid material outlet I1. Within the chamber I and secured to the side wall thereof, a plurality of vertically spaced nonrotatable plates I8 are provided. The plates I8 are each formed with one or more radial openings I9 disposed in staggered relationship with respect to the openings in the preceding and succeeding plates. One or more radially extending arms 20 are provided immediately above each plate, and these vertically spaced arms are secured to a shaft 22 driven by a motor 23 for rotation therewith. Below the upper solid material inlet I6, the wall of the chamber ID is per- .fora't'ed `fas indicated at 24, and :this perforated .portion-'oi the chamberwallfis vsurromided by Aa jacket 25 having :a liquid outlet ippe 'Z6 leading therefrom..

'The :conveyer .1|I ,fassnowniisfpreierablyfoi the endless :drag l'type :comprising :5a fchain .28 for :the Ilike .carrying .ia Aplurality foi `blades or .drag links 29. The .conveyer :'-is housed within a .casing30 :forming fa :lcon'duit which .is :divided intoxan f'elevatingzpassage 31 .and 'a return .passage .'32Lby/an intermediate partition 134. At opposite .ends :of the conveyer lthe'lchain .'2 8 is .'guide'd by pulleys :35 fand 436, 'the upper pulley :35 :being .driven :Ebya .motorl 3'I .in .a 'clockwise .directiorrso thatithe. chain movesupwardly :in passage 3| fand td'ownwardly "inpassage 32 as indicated by `the arrows. The conveyer Ais 'shown Tas :operative 1in a horizontal sand vertical :plane ibut thi-simay be :modified as desired in particulariinstances.

AThe upper portion of th'efc'onveyer passage .3111s l .in .'open communication by way of ports 40, '4| with the rchambers .or Lche'sts I 2, V| 3, r-respectively, :associated with the :opposite sides of the lconveyer Leasing. The chests I2, I3 may either be formed integral with the conveyer casing, as shown, .or they maybe formadas separate memm bers,tcommunicating with theconveyer casing by suitable piping. The conveyerpa'ssage-.32, at .its upper portion, .is likewise in open 'communication with the chests I2, `I3 l.by way of :ports '42, 43, -respectively. .It should, however, :be noted that the ports `'1I|l,1'4| .arepflconsid'era'bly greater verticallengthathan the ports 42, .43, openingv into the chests I2, .I3 atzta point .below'the .lower .ex-V tremities :of ".thezports 4.2, 43 zas will be .hereinafter morelfullydescribed. The .chests L2, I3, respectively, are provided, adjacentthe .lower portions thereof, withspiralconveyers lor 'feeders 45, 46 'operated by :suitablermotors 41, 43, respectively, in a` direction suchfastolteed the .material toward the respective discharge- 'openings 50, -.5 I and vplug valves 52,.53 'or thellike. .The 'valves.52, 53 are yieldingly movable axially of their .respective spiral feeders v45,046 an'dmay beiadjusted as 'to the pressure to .be :applied yagainstlmaterial .fed thereto by varying the .pressure in thelcy'linders of the servomotors55, 56,:respectively,1in ano'bvious manner. Communicating with .the discharge openings 5|), Y5| of the r`zhests12,` |.3 through a spout 51 are one or more driers I4 ofia conventional type which form no vpart of the present invention and therefore need not be further .described. Solvent 'is supplied to the chests I2, I3 of the apparatusfrom asuitable source of ysupply by way of a pump '58 and' piping 59 .communieating with the chests I2, I3 through inlet ,ports 6|, 62, respectively. .'I-hefsolventsupply ports 6|, 62.l are preferably locatedfabove the spiralreeders 45,46 .but belowvthe lower lips 63, 64 .of `theports 42, v43, respectively, .for :reasons -as will hereinafterbecome-apparent. y

The spiral conveyers 45, 46, operating .inrconjunction with the suitablerknown internal formation .of .chests nI2, ,I3 land restricted .discharge openings V`50, 5I, form a mechanism of `known character which .may Lbe referred to V.hereinafter "for 'convenience as: 'fluid expressing, compressed solids ejectingmeans. This vterm (fluid expressing, compressed .solids ejecting means) denes any suitableknownmechanism, or its-Substantial equivalent, .for v,expressing .uids `from amass 0f fluid containing ysolids and ejecting the solids, in compressed, relatively uid free state, .from the space within whichzit--operates In Qpelaiign 'f ihedevice, solvent issunpled throughthefsolventiinlets BI ,152 zto .the .'hests sld, 5| 3, respectively, and raw .solid .material containing the .substance to .be extracted vis fed '.to :the chamber Ii bysuitabIemeans rthrough theupper inlet I6. With valves :52, 531closingthetrespective discharge openings l, '5.| -:both j passages of the conveyer as well as thezchamberr Dare flooded with `solven-'tnp t'othe level of the lmitlet26 :communicating withthe chamber Ill. Since .the solvent escapes through the 'perforated portion L24 of `the extraction 'chamber and is .conductedaway from the unit through the outlet.-26,1it1is apparent that'a continuous flow of .solvent from-the upper portion of the Aconveyer to .the lower lportion thereof and ith'enLthrou'gh thezloweroutlet |"I vand upwardly Withinlthe chamber-.IU to theliquid'outlet is established, with a `.liquid level v.in .both the conveyerland the initialex'traction vchamber'bein'e maintained approximately at 'the point of .discharge-of the liquid, as indicated.

The solid material being fed rto the upper Spor- .tion of the Vchamber II) falls 'by gravity-to the uppermost of the plates 'I8 where itis carried .to theopening I9 by thearm 2|),'falling `bygravity to the nextsucceedingplate vfor similar handling. Thus, it is seen that vthe .material is .advanced downwardly in thecham'o'er ID Yfrom the upper inlet I6 to the lower outlet |.'I in afretarded manner and throughY a bath of countercurrentlymoving solvent. Since the'rst contactbetween .the solid material 'and 'the .solvent loccurs :in this chamber, the greatest-amountvof oil-fis removed by the solvent during this initial treatment.

The material being continuously advanced through the chamber I 0 nnally falls through the lower :outlet f I I intothe horizontal portion of Vthe conveyer I'I. Since the .chain 28 .andhnks ..29 of .the conveyer are being .continuously advanced in aldirectionasindicated-.by the arrows,the imaterial is movedthrough the passage 3 |.,fbeingfcar ried :upwardly therethrough by thelinks v29. fAs the 'material reaches .the upperportion of the passage '3| 'adjacent the ports `1ML-74|, lit isvdischarged through these ports `to the .respective chests I.2,.|3, falling by .gravity .intothe continuously .operating spiral feeders V45, 46 which fad- Vance the material 'to the respectiveopenings 50, 5I for discharge therethroughto the drierlagainst the pressure. of 'the `valves .52, -:53, respectively.

Obviously, .as the operations are being carried out with .the solidmaterial 4being advanced upwardly .through the closed passage 3| of the iconveyer, the fresh solvent being supplied -at-6I, .62 is prevented from flowing freely downwardly within the passage 3| which is filled withslid material yand solventthroughout its length, and the solvent therefore rises in `the `4chests |2,-.I3, submerging 'the .spiral .feeders and lthe lmateri'al being handled therebyand overflowing vthrough the ports v42, 43 into the vempty .passage32 of the conveyer. It is therefore` .apparent that, during'the operation of the device, the lowerlips 63, 64 of .the `ports "42, 43, respectively, act as dams lover which the .overilowliquid from the chests I2, I3 is conducted tolftlie empty return passage 'of the conveyer. From the `passage ."32 the vliquid yhows downwardlywithin the conveyer and 'thence upwardly within .the 'initial .extraction chamber to 'the liquid outlet 26 as .hereinab'ove described.

`Referring now .to Figs. .5 to 'lof the. drawings, a .modified form 'of apparatus (iluid expressing, compressed solids ejecting means.) which may .be used at .the upper `portion .of the .conveyer for separating .the .liquid from the solid material during discharge to the drier is illustrated. In the modied arrangement, the material moving passage |3| and the return passage |32 of an elevating conveyer I are separated by an intermediate partition |34 as in the apparatus hereinabove described with reference to Figs. 1 to 4 of the drawings. However, in the modification shown in Figs. to 7, a single final extraction and separation chest ||2 is provided, such chest being disposed between the passages |3| and |32 at the upper portion of the conveyer and forming a part of the intermediate partition |34. The chest or chamber ||2 is in open communication with the passage |3| by way of a port |40 and the chest ||2 is likewise in communication with the passage |32 through a port |42. The port |40 is larger than port |42 which has its lower extremity located somewhat above the lower extremity of port`|40. Within the chest ||2 and adjacent the bottom thereof are provided a, pair of spiral conveyers or feeders |45, |46 disposed in a common plane and driven from a common shaft but with the spiral flights thereof formed for delivery in opposite directions. The spiral feeders |45, |46 are adapted to feed material toward discharge openings |56, |5| and plug valves |52, |53, respectively, into spouts |51, |51 communicating with a drier, not shown. The valves |52, |53 may be adjusted by supplying more or less pressure to the cylinders of the respective servomotors |55, |56. Fresh solvent is supplied from a suitable source to the conveyer passage |3| adjacent the chest ||2 through the inlet port |6|.

In operation, the modified device functions substantially like the preferred arrangement. The solid material is advanced through a body of countercurrently moving solvent in the initial extraction chamber and is conveyed upwardlyin the elevating passage |3| of the conveyer. The material being moved through the passage |3| is discharged into the chest ||2 through the port |40 and settles by gravity in the spiral feeders |45, |46 submerged in a bath of fresh solvent being continuously supplied through the supply port |6|. The spiral feeders |45, |43 discharge the solid material into the spouts |51, |51 through the openings |50, |5| against the pressure of the valves |52, |53, respectively. The liquid from within the chest |I2 overows the lower edge or discharge lip of the port |42 into the return passage |32 of the conveyer and circulates through the passage |32 and the initial extraction chamber to the liquid outlet provided therein.

From the foregoing detailed description, it is apparent that the solid material, in both forms of apparatus, continuously remains completely immersed in a bath of solvent from the time it reaches the liquid level in the chamber I0 until it is discharged from the chests |2, I3 or the chest ||2 to the drier. In addition, it should be noted that the solvent bath is of increasing freshness as the material is advanced to its nal discharge point, with the fresh solvent being supplied adjacent the point of discharge of the exhausted solids. By immersing the material in a nal solvent bath at the point of discharge thereof, a nal extraction and displacement of oil is effected. Furthermore, by keeping the material completely immersed in a bath of liquid during all of the operations, the material is readily handled by all parts of the apparatus, and the difculties heretofore encountered with prior devices are obviated. By the mechanical squeezing means herein provided, the length of the conveyer may be reduced to a minimum; and because of the effective separation obtained by such squeezing device, the size and number of nal driers for evaporating the comparatively small amount of solvent remaining with the treated solids may also be substantially reduced. The compression mechanism is continuously operating while submerged, but the amount of pressure necessary v for efficient separation of liquid from the solid material is exceptionally small because of the low head under which such device is operating. Because of the minimum' pressure against which the material is discharged in the present device, the desired characteristics of the material remain unaffected during the process. It is furthermore apparent that the mechanical separator may be controlled independently of the other apparatus both as to speed and pressure, and it is located in an accessible position for any necessary repair or the like. While the liquid level in the return passage 32 of the conveyer has, as a matter of convenience, been shown and described as being the same as that in the chamber l0, this will obviously vary somewhat dependent upon various circumstances, such as the amount of solid material in the chamber l0 and the rate at which it is advanced therethrough against the countercurrently moving liquid. The level of liquid in the passage 32 will, however, normally be located somewhere between the level of the liquid outlet 26 and the lower lips of the ports 42, 43 during operation of the apparatus. The various parts of the apparatus may obviously be altered somewhat without departing from the scope of the invention; and although two nal extraction and separation chests have been shown and described in the preferred embodiment, the device may be modified by eliminating one of these chests or chambers and its attendant parts, if desired. It is apparent that in both forms of the device herein illustrated and described, the solid material is removed from the initial extraction chamber and elevated through a column of solvent from which the solids are discharged by pressure beneath the upper extremity of the liquid column. Likewise, in both forms of apparatus the height of the column of liquid is utilized for maintaining the initial extraction chamber constantly filled with liquid.

Although the invention has been shown and described in conjunction with a particular type of initial extraction chamber and apparatus and a continuous conveyer of the drag link type, it may obviously be utilized with similar equipment in like manner and with equal success; and it should therefore be understood that it is-not desired to limit this invention to the precise steps in the method or the exact details of construction of the apparatus or the application and mode of operation herein shown and described for various modifications within the scope of the claims may occur to persons skilled in the art.

It is claimed and desired to secure by Letters Patent:

l. ln a device for treating solids with liquid, an upwardly extending conduit having an inlet for solids and an outlet for liquids at a lower portion thereof, an elevating conveyer in said conduit for moving solids upwardly from said solids inlet, a fluid supply connection opening into an upper portion of said conduit, a pair of chests disposed on opposite sides of said conduit at an upper portion thereof, each said chest being connected with the interior of said conduit through a port for receiving solids and uid from said conveyer, a restricted solids outlet opening through a wall of each said chest below the level of said ports, and fluid expressing compressed solids ejecting means in each said chest and below the level of said ports for ejecting compressed solids through said restricted solids outlet openings.

2. In a device for treatment of solids with liquids, an elevating conveyer confined within a conduit havinga uid outlet and solids inletfat its foot, said conduit having separate elevating and return passages, a fluid feed connection opening into anfupper portion of said elevating passage, a char'iber formed within said conduit and extending transversely thereof between said elevating and return passages at an upper prtion thereof, aAk port connecting said chamber with the interio'rof said elevating passage for receiving solids and fluid therefrom, restricted openings in opposite ends of said chamber and penetrating opposite side walls of said conduit REFERENCES CITED The following references are of record in the le of this patent:

FOREIGN PATENTS Number Country Date 2,156,236 Bonotto Apr. 25, 1939 20 2,184,248 Bonotto Dec'. 19, 1939 2,276,298 Frazier Mar. 17, 1942 

1. IN A DEVICE FOR TREATING SOLIDS WITH LIQUID, AN UPWARDLY EXTENDING CONDUIT HAVING AN INLET FOR SOLIDS AND AN OUTLETS FOR LIQUIDS AT A LOWER PORTION THEREOF, AN ELEVATING CONVEYER IN SAID CONDUIT FOR MOVING SOLIDS UPWARDLY FROM SAID SOLIDS INLET, A FLUID SUPPLY CONNECTION OPENING INTO AN UPPER PORTION OF SAID CONDUIT, A PAIR OF CHESTS DISPOSED ON OPPOSITE SIDES OF SAID CONDUIT AT AN UPPER PORTION THEREOF, EACH SAID CHEST BEING CONNECTED WITH THE INTERIOR OF SAID CONDUIT THROUGH A PORT FOR RECEIVING SOLIDS AND FLUID FROM SAID CONVEYER, A RESTRICTED SOLIDS OUTLET OPENING THROUGH A WALL OF EACH SAID CHEST BELOW THE LEVEL OF SAID PORTS, AND FLUID EXPRESSING COMPRESSED SOLIDS EJECTING MEANS IN EACH SAID CHEST AND BELOW THE LEVEL OF SAID PORTS FOR EJECTING COM- 